Evaluating cover crops forage nutritive value in Oklahoma winter wheat systems

Winter wheat (Triticum aestivum L.) is a valuable crop in the southern Great Plains that grows from fall to spring, with fields then typically fallowed through the summer. Adding grazeable cover crops to the fallow period could increase farm profitability. The objective of this study was to determine eight different cover crops' nutritive value and simulated stocker calf performance. Cover crops were established in late spring 2016 and 2017 in Chickasha and Perkins, OK. At 6 wk after planting, two simulated grazing regimes based on cutting height were used: severe (<= 2.5 cm) and recommended (7.5 cm). Legumes had the highest nutritive value in comparison to warm-season grasses and grass-legume mixtures. Legumes resulted in higher simulated daily steer gain (DSG) and total steer gain per area (TSGA) values than grasses and mixtures at Perkins. At this location, legumes had superior forage nutritive value, compensating for lower yields. At Chickasha, grasses and mixtures had higher TSGA values (246.7 +/- 6.9 kg ha(-1)) and lower DSG (0.17 +/- 0.04 kg steer(-1) d(-1)) values than legumes (131.6 +/- 25.3 kg ha(-1) and 0.48 +/- 0.02 kg steer(-1) d(-1)). This finding implied that grasses and mixtures with lower individual DSG required much higher stocking rates than legumes to achieve higher TSGA values. This increment in stocking rates could increase costs, drastically decreasing profits. Consequently, legumes might be a viable option due to their balanced forage yield and nutritive value relationship. However, consideration must be given to supplemental energy to better balance the TDN/protein ratio requirements of the stocker calf.